Crayon



Patented Aug. 24, 1943 U NIT E D STATE S PATEN OF F [C E CRAYON PerJohan Berggrcn, New York, N. Y. No Drawing. Original applicationOctober6,1937,

Serial No. 167,538. Divided and thisrapplication September 19, 1940,Serial No. 357,354

4 Claims.

This invention relates to improvements in a crayon especially preparedfor use in making light controlling elements or masks such as areemployed in the reproduction of photographic films from negative films.

An object of the invention is the provision of a crayon of this typewhich is employed for marking upon a ground glass or ground film plateor sheet of the ground side thereof for the'purpose of changing thediffusing action of the ground surface at the marked points to a partialor substantially full transparency.

A still further object of the invention is to provide a newmaterial'composition in crayon form which may be easily applied toground glass or ground film at desired areas indifferent concentrationsor amounts and which will not smudge or smear, and is, therefore,relatively permanent under all normal conditions of usage.

Still another object of the invention is the provision of a materialcomposition of this type for such a use which may be applied in a mannerso as to eliminate any sharp line of division between the diffusingareas of the plate or film and the transmitting areas produced by theapplication of the material.

A still further object of the invention is the provision of a materialcomposition of this type for use in the manner stated, by means of whichcloud effects and variations in the background density of prints fromnegative films of scenes may be secured in accordance with the artisticdesires of the operator.

These and many other objects as will be apparent from the followingspecification are successfully secured by means of the invention hereindisclosed.

This invention resides substantially in the combination, construction,arrangement and relative location of parts, all in accordance with thedescription herein.

This application is a division of my United States patent applicationSerial No. 167,538, filed October 6, 1937, for Photographic diffusingmask and method of preparing the same, which is co-pending.

As is well known in the photographic arts, it is often desirable toproduce positive prints from negative film through a diffusing element,first for the purpose of softening or diminishing the harsh lines, andthe sharp or strong lines or portions thereof, and second to prevent thereproduction on the positive of the re-touchers marks on the negative.portrait, the negative film frequently shows harsh lines or wrinkles inthe face, which it is desired to eliminate in the prints therefrom. Thisis frequently done by placing a diffusing element over the sensitizedpositive film'and exposing it to the For example, in the case of a Inegative film therethrough. The same sort of difiusingelement isemployedwhen it is desired to prevent the reproduction in the positive print ofthe re-touc'hers lines'applied to the negative film. It ls,'of' course,well known in the art that the re-touchefls linesare the result of themarking out on the negative of undesired lines, such as wrinkles, skinblemishes, and otherdefects in the skin Ofthesubject.

At the present time there are two generally known'methods of modifyingsuch elements. In the one, a clear sheet of transparent material, suchas glass, which isplaced over the negative film has brushed thereon 'orotherwise applied thereto, in any suitable .manner, as for example bymeans of abrush, a diffusing film of some suitable material, such forexample as a fat, an oil, a wax, a soap, or thelike. This diffusing ortranslucent film is painted onto the glass over the areas to bediflused,which in the case of a portrai'twould be the skin of the face. Thisleaves the glass clear and transparent at the eyes, the mouth, the nose,and such other points as are desired.

'Thedifficulty with this method is that, as will be apparent, verysharplines of division occur between the transparent and the diffusing ortranslucent areas, which produce highly undesired effects "in thepositive print taken there through. It would be highly desirable if away were known to effect a softening of the division line between thetransparent and the translucent areas, and it would be highly desirableto be able to effect-a gradation or shading in the translucent areas,This is not possible by use of the film materials 'of the type explainedabove and now known.

A second method which is sometimes employed for modifying diffusingelements of this type consists in applying over the negative a groundglass or film and'then applying thereto an oil, a fat, or a wax atdesired areas to render it transparent. For example, the areas over theeyes,-the 'mouth,-and the nose are painted in or filmed with a fat, 'awax, or the like, which renders these areas transparent, leaving therest of the plate or film translucent because of its ground surface.Here again it is not possible to effect a gradual or shaded line ofdistinction between the translucent and the transparent areas. The lineof demarkation is sharp, which is undesirable for many obvious reasons.Furtherrnore, all materials heretofore known for the purpose ofrendering ground glass plates or films transparent easily smudge andsmear, making it extremely difficult to handle the element during thereprinting operations. Furthermore, these materials used to render theground glass plate or film transparent are hard to handle and apply andrequire highly skilled technicians in their use.

In either case of the known art it is extremely diincult to correct anyerrors which the operator may make in the production of the element, sothat frequently it is necessary when an error is made to apply a newplate over the ne ative and start all over again.

A description will now be given of the material and how it is prepared.As explained above, prior to this invention there was no known materialfor filming clear glass plates or film by rendering ground glass platesor films translucent which would permit of a variation in the lighttransmitting qualities thereof. Furthermore, it was explained above howsuch materials as are used for this purpose readily smear and smudge andare hard to apply. The material of this invention may be made in stickor pencil form as disinguished from the liquid forms of the materialscommonly used, and may be easily applied. A very importantcharacteristic of this material is that it does not smudge and smear,and will remain on the plate or film for long periods of time withoutdeterioration or destruction, even though it is extensively handled.

Furthermore, this material may be readily removed from the plate when sodesired by the use of, among other things, a hydrocarbon solvent such ascarbon tetrachloride. moved wholly or in part by an ordinary rubbereraser.

This material consists principally of two basic substances which arecombined in accordance with the following disclosure, namely, carnaubawax and stearic acid. Either of these substances alone to a veryuncertain degree will produce the desired effect, but each of themseparately has particular defects which make it impractical for thepurposes of this invention. The carnauba wax is very hard and requires alot of effort and hard pressure to work it into the cavities of theground glass or film. It is also very brittle and chips and breakseasily when worked under pressure. When once applied, it is hard toremove and shade. The stearic acid works easier but is inclined tosmudge and smear and does not produce a clean and clear transparency.The result is somewhat like strays in glass and will impair a trueoptical reproduction of the negative when present. However, severalsuitable combinations of these two basic materials can be combined whichdo not have these defects. I have found that very desirable results aresecured from the following combination, such as producing a smooth,clean and clear transparency, free from the tendency to smudge andsmear, applicable with a minimum of pressure and effort to the groundsurface, and which can be easily removed and shaded. This combinationcomprises, for example, five parts by weight of carnauba wax and onepart by weight of triple pressed stearic acid, melted and mixed, and toeach ounce of this mixture ninety drops of any suitable vegetable oil,such as olive oil which is a non-drying oil, are added and mixedtherein. There may then be added to the mixture, if desired, a suitabletransparent dye or pigment, preferably an oil soluble dye, or onesoluble in a. hydrocarbon. The amount of dye or pigment added is notcritical but may be varied, de pending upon the various transparenciesdesired. In other words, in addition to the ability for effectingtransparency graduations by shading, further variation may beaccomplished by the It can also be recoloring of the material itself,thereby varying its own light transmitting characteristics.

The amount of vegetable oil may be raised depending upon the oil contentof the stearic acid. Therefore, the amount used will vary depending uponthe ability of the mixture to absorb it. The controlling factors as tothe amount of oil used are that the final combination should give cleanpartial or complete transparency without too much pressure inapplication and without leaving an excess of material on the groundsurface.

This melted mixture is then poured onto a thin sheet or body of fibrousmaterial, such as cotton, which has preferably been placed in a mould.It is desirable that the mould be warm so that the material thoroughlyimpregnate the cotton fibres before it is chilled. If desired, a glassor other smooth plate may be placed down on the warm wax to hold themass into a thin sheet until it has hardened. The sheet is then cut intosticks, which are placed in a mould of the desired size, as for exampleone having a cavity is of an inch to of an inch, and of any desiredlength. The mould is then placed in an oven so that the wax softens andassumes the form of the mould. It is removed therefrom and then cut intosuitable lengths, as for example lengths of one and one-half inches.This provides a wax crayon or pencil having embodied therein a mass offibres which are employed to give the crayon greater physical strength.It has been found that their presence does not interfere with theapplication of the wax to the ground glass since the short ends of thefibres as they wear off disappear. Such a crayon can be used in the handor in a suitable holder therefor. The sharpened end is worked over theareas of the ground glass plate or film to fill in the roughened surfacein the manner explained above.

From the above description it will be apparent to those skilled in theart that the principles of this invention, and the methods of proceduremaybe widely varied without departure from the scope thereof. I do not,therefore, desire to be strictly limited to the disclosure as given forpurposes of illustration, but rather to the scope of the claims grantedme.

What I claim is:

l. A crayon of the type described, comprising a mixture of substantiallyfive parts by weight of carnauba wax and substantially one part byweight of triple pressed stearic acid, and having approximately ninetydrops of olive oil per ounce of mixture incorporated therein.

2. A crayon of the type described, comprising a mixture of substantiallyfive parts by weight of carnauba wax and substantially one part byweight of triple pressed stearic acid, having approximately ninety dropsof olive oil per ounce of mixture incorporated therein, and havingincorporated therein a mass of fibres.

3. A photographic negative comprising crayon of the type describedcomposed of a mixture of substantially five parts by weight of carnaubawax and substantially one part by weight of triple pressed stearic acid,and having less than ninety drops of a non-drying vegetable oil perounce of mixture incorporated therein.

4. A photographic negative comprising crayon of the type describedcomposed of a mixture of approximately five parts by weight of carnaubawax and one part by weight of stearic acid,

PER J OHAN BERGGREN.

